The aims of this application by the Forsyth County Field Center are to recruit and examine 666 white and African American individuals selected according to the study design described in this application. The Forsyth County Field Center will contribute 500 white, and 166 African-American study participants, stratified into families with 2 or more hypertensive siblings, untreated relatives, and controls. The source population will be individuals previously examined by the Family Heart Study and the Atherosclerosis Risk in Communities Study, and their siblings. Previously collected data by these parent studies will make it convenient and efficient to identify individuals in the required categories according to hypertension status, treatment status, and availability of siblings defined according to previously reported history of hypertension. The examinations will take place at the Forsyth County Field Center, one of six field centers participating in the Network on Genetic and Interacting Determinants of Hypertension. This field center currently serves as the recruitment and examination facility for the Family Heart Study and the ARIC Study. Recruitment and examination of study participants will be carried out according to a standardized protocol, common to all Network field centers, and subject to the quality control procedures in place for the Network as a whole to ensure that data can be appropriately pooled. Analytic methods will cover genetic association and model-free sibship linkage with adequate statistical power to detect specific genetic loci which promote hypertension, for the African American and non-black populations inducted in this Network. Epidemiologic analyses will follow, to identify gene-environment interaction in sub- populations with, and without confirmed genes for hypertension in relation to specific lifestyle factors putatively associated with the likelihood of expression of genetic predispositions to hypertension.